Later edit:
The above are fixes for what appears to be a blunder in how your page is constructed. There is something strange going on; Firebug shows an empty <head> tag, and what should be in it is in the <body> tag. In addition, no charset is ever specified (should be in the first 512(? or is that 1024?) bytes on the page. Either of these will trigger IE to render the page in quirks mode. Fix them and you won't need the H5B fixes above.

An even later edit:
The above is incorrect; after looking at the page source what really seems to be happening (and what fooled Firebug) is this:<div class="bb"></div><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">, i.e. there is an empty <div> at the top of the page. Remove it (or move it to <body>) and your problem will go away.